In this response to NHLBI RFA Number HL-98-010, we propose, as a field center: In Phase I: To conduct a two year intervention planning phase to: (a) identify potentially modifiable social and behavioral determinants of the behaviors and processes that will form the core of the intervention program, particularly those that may have been previously unrecognized or that have different characteristics in African American girls than would be assumed based on studies in Euro American girls; (b) identify important contextual variables (e.g., cultural, situational, familial, or developmental factors that will clearly influence adoption and long term adherence, but which cannot be directly addressed by the intervention) and specify their implications for the intervention design and implementation; (c) for both the social/behavioral and contextual variables, distinguish between cultural variables that are common to African Americans across socioeconomic status from those that seem to apply primarily to high or low SES girls or their families, in order to clarify what differences in assumptions and approaches would apply to interventions stratified or not-stratified on SES; (d) refine proposed data collection methods to improve the validity and appropriateness of all measures for pre-pubertal African American girls, considering physiological and cognitive development, body composition issues, and psychosocial factors; (e) revise the proposed design, recruitment, intervention, and measurement plans as indicated; and (f) feasibility test all aspects in a formal 12 week pilot study with participants similar to those to be included in the Phase II study. In Phase II: To conduct a two year (Phase II) randomized clinical trial of two family-based interventions compared to a standard care condition. The primary outcome measure will be the between group differences in BMI and DEXA at 1 and 2 years of follow up. Secondary outcomes will be percent body fat, fasting insulin, glucose, and c-peptides. Intermediate outcome measures will include between group differences in dietary intake and physical activity. Measures of intervention safety and potential negative side effects of intervention will include measures of bone mass, sexual maturation, eating disorders, and rates of smoking. Because the type of intervention that will be effective will involve an interactive process of tailoring and responding to participant needs and interests, rather than fixed content offered in a fixed format, an additional aim of Phase II will be to document the interventions to allow for later dissemination. This will be accomplished through continued monitoring of the implementation process and development of a scheme for describing how the process evolves and how it can be replicated.